Google and Exchange accounts are linked, but must be edited twice

I have Sony Xperia T3 with Android Kitkat on the board.

I've linked my Google account as well, as my Microsoft account, which was recognized as "Exchange ActiveSync". Since I've had almost all contacts stored in Google and in my Microsoft account, Android was able to link them all correctly and display as only one contact in my address book.

But whenever I'd like to edit any of my contacts, I can choose between Google and Exchange account for editing. So, if, e.g. I'd like to change name or add a new phone number to a contact, I need to do it twice: for Google account to sync it with Google, and to Excange account to sync it with Microsoft.

How can I avoid this double-changing?